Alidade bearing indicator



Aug." 15, 1950 D. JAssY ALIDADE BEARING INDICATOR '2 Sheets-Sheet 1 File d Aug 9 1945 122 .INVENTOR 3 substantially stand-ard equipment, and the specific form illustrated is that of a Sperry gyrocompass repeater.

The improvements of the present invention involve the mounting of a telescopic alidade or transit to turn about a vertical axis coaxial with the axis of rotation of the compass card. For this the mounting on the compass card 48, of a boss or plate 58. The boss 58 may comprise a disc or washer secured in place, as by rivets 52, or other'-' wise. Additionally, it may be formedintegrally with the compass card 48. A stud 54 is centrally mounted in the member 58 for rotation therewith and is provided with a slot 56 or other coupling means. The only other alteration in the standard compass structure is the cutting of aligned apertures 25, 21 in the geometrical center of the windows 24, 26. A water-tight nut 68 is set in the so-formed aligned center apertures of the repeater glasses. This nut has a bearing flange BI and a locking ring or flange 62. Gasket material 64 is disposed between the repeater glasses 24. 26 and the locking ring 62 to provide a watertight fitting. The nut is internally threaded at 65 to receive plug 66 having cooperating thread 61. The plug 86 provides a water-tight closure for the repeater'glasses when the alidade is not in use. The specially prepared compass or repeater compass will be seen to be otherwise standard in every respect and to be susceptible of its ordinary use without modification of its essential parts or construction.

The alidade or theodolite comprises the usual telescope tube I8 having objective I2 and eyepiece The barrel of the tube is provided with the usual cross hairs, not shown, and is mounted in a collar or yoke I6 provided with horizontal trunnions I8. The trunnions are mounted for rotation in appropriate bearings 84 seated in notches in the ends of legs 8|, 82 of U-shaped yoke 88. Bearing clamps 83 are secured in place over said bearings as by set screws 86. To clamp the telescope on any desired angular elevation, I have shown the extension 85 of one trunnion threaded to receive wing nut 81 and the other extension 85 tapped to receive set screw 88 on which is mounted'indicator arrow 98. A scale 9| comprising a quadrantal vertical are, as shown, is mounted on leg 82 of yoke 88 secured in place by rivets or screws 92.

Detachable means are provided for causing the compass card to turn the sighting means or telescope in azimuth, when desired. To this end yoke 88 is mounted on a post or shaft 94, the lower end of which is formed as a generally cylindrical cap 95. The cap has a bearing surface 96 at its bottom or open end, and an inner cylindrical bearing surface 91. An internal centering stud 93 is formed internally of the cap. An index or indicator arm I85 is secured on cap 95, as by rivets I81. The indicator arm has a finger or index I89 which is in the exact vertical plane of the central longitudinal axis of the telescope I8. This vertical axis will also coincide with the axis of rotation of the compass card 48 and the stud 54 mounted thereon.

The alidade support is rotatably mounted on the compass windows or glasses in the following manner. Tube or sleeve I I8 of brass, aluminum, or any other suitable metal, is screw-threaded at one end, as indicated at I I I, for engagement with screw thread 65 of clamp 68. The tube H8 is coaxial with collar 95 and post 94 of the alidade support and with the axis of compass card 48.

4 Adjacent its upper end, the tube, or hollow post, is provided with an external flanged collar IIZ having a bearing surface upon which bearing surface 96 of cap 95 may freely move, cap 95 in combination with tube ,II8 and its flange II2 hence constituting a mounting for the sighting Y means permitting rotation of the sight with or purpose, the improvements herein comprehend independently of the compass card about its axis.

I The upper periphery of the tube, indicated at II3, is adapted to provide a bearing surface for the inner surface 91 of the cap 95. While these surfaces have been shown as lapped bearing surfaces, the bearings may be provided by appropriate thrust and side antifriction ball or roller bearings. The supporting post or tube H8 will be screwed in place in the water-tight nut 68 and the alidade support or yoke 95 fitted thereon. The alidade telescope I8 is thus freely rotatable on the post or support H8, and the index I89 of the indicator arm will coact with the markings of the compass card 48 to give correct bearings.

The alidade telescope is not only freely movable but is adapted for mutual movement and rotation by and with the compass card. To this end, a shaft II5 having an end key section H6 is fitted into the slot 56 of stud 54, mounted on compass card 48. The shaft II5 will be of suificient length so that its upper or free end I I1 will extend above centering stud 93 of cap 95. The upper end of shaft I I5 will desirably have a frictionless or low-friction bearing engagement with the inner surface of centering stud 93. The stud 93 may comprise an internal collar into which shaft H8 is received in aligned bearing engagement. The cap is provided at one side with a threaded aperture 98 adapted to receive set screw I8I, aperture 98 being preferably aligned with centering stud 93. By tightening the screw with thumbpiece I88, the stud 94 and its supported telescope are clamped to rod H5 which has its lower end nonrotatably engaging the slot 56 in boss 54. Preferably a second set screw I82 is provided to fix the telescope when not in use, said screw when screwed in engaging fixed sleeve I I8. These screws are preferably provided with intermeshing gears I84, I86, so that both cannot be engaged at the same time and thus throw the repeater compass out of step. When knob I88 is rotated clockwise, screw I8I will be moved into engagement with shaft II5 thereby locking cap 95 to the shaft. Simultaneously, the screw I82 will be rotated counter-clockwise in its threaded aperture 99, out of engagement with post II8. Upon rotating knob I08 counter-clockwise, screw I8I will be moved out of engagement with shaft H5 and screw I82 will be moved into engagement 'with the upper section H3 of post or supporting shaft H8. The knob I88 may be rotated to an intermediate position so that there is no locking engagement of either screw I8I or screw I82 with shaft H5 or post II8.

With the mounting system shown, it will be seen that in the unlocked position the telescope I8 is rotatable in azimuth around the aXis of the compass card and its compass bearing can be read where accurate bearing is wanted. The clamp screws controlled by knob I88 are rotated so that screw I82 is moved to maintain cap 95 and post H8 in looking engagement. This permits the individual operator to make his fix or reading and then read the bearing from the compass card. Where it is desired to bring the alidade to a desired bearing point, the knob I88 will be rotated to lock shaft H5 and cap together and unlock cap and post II8. In this 5 locked position, movement of compass card 40 will rotate shaft H5 and telescope 19 through its mountings 94, 95.

As shown in Fig. 5, a modified pointer construction may be used. In this construction, a pointer or dial hand I29 has an apertured hub I 2I which is fitted on and over stub post 54. The pointer is freely rotatable about the post and may be prevented from vertical displacement by a transverse pin I22 inserted through the stub post 54 above the upper surface of the hub iii. The hub I2! is provided with one or more apertures I23 adapted to receive finger 525 of arm I25 secured to the lower portion of centering stud 93 and movable therewith. The arm I25 may desirably be formed as a single arcuate cylindrical section, as indicated by the dotted lines I26, in order to provide the necessary structural strength and prevent whip or friction, as would be the case were a single rod or finger used, and any binding developed between the several parts.

With the improved intermeshed control of the locking device, it is impossible to freeze the mechanism so that the compass card, driven by the repeater motor, would be locked or braked against the fixed post I I0.

As indicated hereinabove, the improved alidade is demountable and can be stored when not in use. The plug 66 is set in place, and the repeater compass is then used in the normal way. To assemble the alidade, the shaft I15 is inserted in slot 56. The post H is then fitted over the shaft and screwed into the nut 60. Cap 95 is fitted on the top of the post, riding on collar IIZ. When the device is to be disassembled, the cap is removed and the post III! unscrewed from nut 60. The shaft H5 is then removed and the plug is screwed back into the nut.

Inuse, with the device properly assembled, bearings are taken by revolvin the telescope until the reference object is in the cross hairs of the telescope. The clamp screw IOI is tightened and the bearing is taken from the pointer I09 or I20 as the case may be. In following a prescribed course, the device may be used to insure turning at the proper bearing points in the following manner. The telescope is turned until the pointer is on the desired heading on the compass card. The clamp screw IOI is locked and left in that position.' When the object or reference moves into the cross hairs, the desired bearing point has been reached. This is called "riding into the bearing as explained above. When relative bearings, with respect to the ship only, are desired, the compass card may be arbitrarily set at 0 heading relative to the lubber lines I'II'I by the knob 44, and screw IOI tightened with the telescope pointed fore and aft as indicated by the position of the index I09 relative to the lubber lines I 1-I1. Then the telescope is rotated to bear on the object carrying with'it card 40. The difference between the bearings can then be read directly on the compass card by reading th compass point opposite one of the lubber lines II-Il. For celestial navigation, the altitude of stars can be obtained by sighting with the telescope, tightening the clamp screws to hold the bearing. and reading the altitude from the scale 9|. When it is desired to find a known star or Venus in the day 7 time, the telescope is set at the correct bearing and approximate altitude and a sight is taken through the telescope.

Since many changes could be mad in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope ther-- of, it is intended. that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a gyro-compass repeater having a glass cover, the combination with a repeater compass card, of a central boss thereon, a shaft coupled to the boss, a central threaded clamp nut through the center of said cover, means connected with said nut including a supporting tubular post having a bearing flange surrounding the shaft, sighting means, means mounting said sightin means for free rotation on the bearing flange of said post independently of the compass card, and clamping means for detachably securing the sighting means mounting to the said shaft.

2. An alidade attachment for repeater compasses as claimed in claim 1, having alternative clamping means for clamping said sighting means mounting to said post.

3. In a gyro-compass repeater having a glass cover, the combination with a repeater compass card, of a central boss thereon, a shaft adapted to be detachably coupled to the boss, a central threaded clamp nut through the center of said cover, means connected with said nut including a supporting tubular post, sighting means, means mounting said sighting means for free rotation on said post independently of the compass card, and clamping means for detachably securing the sighting means mounting to the said shaft, whereby said sighting means may be coupled to said card to rotate therewith or be freed therefrom for independent setting.

4. In a repeater compass, in combination with a mounting, a driving shaft, a compass card mounted to rotate with said shaft, 2. second shaft detachably mounted on said card and rotatable therewith, a tubular sheath for the second shaft fixed relative to said mounting, a revolvable cap mounted on the sheath, an index mounted upon the cap so as to rotate therewith in a plane parallel to the card, a sighting means attached to the cap and movable with the index, and means for locking the cap to said sheath on to the said rotatable second shaft, as desired.

DAVID JASSY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

